Nitration of Aromatic Compounds Using a Recyclable Catalyst

Nitration of Aromatic Compounds Using a Recyclable Catalyst 

Atom-economic reaction Recyclable catalyst Rotary evaporator (optional) 

In the present experiment, we employ a Lewis acid, ytterbium (III) trifluo-romethanesulfonate, as a catalyst for the nitration of a series of aromatic substrates with nitric acid. This catalyst will be recycled (recovered) and reused. 

The solvent used in this reaction, 1,2-dichloroethane, is not environmentally friendly, but the solvent can be recovered using a rotary evaporator. 

A proposed mechanism for this reaction involves the following three steps to generate the nitronium ion. The trifluoromethanesulfonate (triflate) ions act as spectators. The ytterbium cation is believed to be hydrated by the water present in the aqueous nitric acid solution. Nitric acid binds strongly to the hydrated ytterbium cation, as shown in equation 1. A proton is generated, as shown in equation 2, by the strong polarizing effect of the metal. Nitronium ion is then formed by the process shown in equation 3. Although the nitronium ion may serve as the active electrophilic species, it is more likely that a nitronium carrier, such as the 

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Exp. 28, "Chiral Reduction of Ethyl Acetoacetate" Exp. 29, Nitration of Aromatic Compounds Using a Recyclable Catalyst"... 

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